Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents	$ 280,995	$ 402,579
Marketable securities	972,885	982,725
Prepaid expenses	25,427	19,762
Receivables and other current assets	21,473	13,931
Total current assets	1,300,780	1,418,997
Marketable securities	287,922	506,123
Property, plant and equipment, net	129,135	246,622
Intangible assets, net	16,480	13,169
Goodwill	13,128	13,128
Operating lease right-of-use assets	190,979
Restricted cash and other non-current assets	84,920	44,805
Total assets	2,023,344	2,242,844
Current Liabilities:
Accounts payable	29,458	17,831
Accrued expenses and other current liabilities	91,105	99,393
Operating lease liability, current portion	18,872
Deferred revenue, current portion	9,484	18,602
Collaboration research advancement, current portion	13,190	10,605
Total current liabilities	162,109	146,431
Deferred revenue, net of current portion	13,739	16,338
Collaboration research advancement, net of current portion	28,333	33,349
Contingent consideration	5,740	5,230
Operating lease liability, net of current portion	175,350
Financing lease obligation, net of current portion		153,319
Other non-current liabilities	1,699	3,107
Total liabilities	386,970	357,774
Commitments and contingencies (Note 8)
Stockholders’ Equity:
Preferred stock, $0.01 par value, 5,000 shares authorized; 0 shares issued and outstanding at June 30, 2019 and December 31, 2018
Common stock, $0.01 par value, 125,000 shares authorized; 55,228 and 54,738 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively	553	547
Additional paid-in capital	3,489,112	3,386,958
Accumulated other comprehensive loss	(819)	(3,627)
Accumulated deficit	(1,852,472)	(1,498,808)
Total stockholders’ equity	1,636,374	1,885,070
Total liabilities and stockholders’ equity	$ 2,023,344	$ 2,242,844